The fighters belonging to ISIL, or the Islamic State of Iraq and the Levant, attacked government forces with a suicide car bombing in Tal al-Rayyan and that three other car bombs were found there, according to Aridhi.

The CTS, the most-seasoned force in Iraq, has suffered no losses since the renewed push on west Mosul was launched on Sunday, according to Aridhi.

He said some fighters had been wounded, however, some of them by the weaponised drones that ISIL - also known as ISIS - has increasingly resorted to in recent weeks.

Earlier casualties

Late on Thursday, ISIL rocket attacks killed at least dozens of Iraqi soldiers, a day after the army secured Mosul airport.

Al Jazeera's Osama Bin Javaid, reporting from Erbil, said that ISIL targeted the troops from multiple fronts, including soldiers who were stationed at Mosul airport, one of the Iraqi army's most significant achievements in its first phase of the offensive.

"It is one of the largest death tolls you've seen in the last six days of this push towards western Mosul," he said.

He said that while ISIL had claimed that it had killed almost 40 Iraqi soldiers, "Iraqi government officially does not accept or deny any of these casualty figures [although] military sources have been telling us that dozens of soldiers have died in these ISIL attacks".

The attacks came after Iraqi forces stormed the city's airport and a nearby military base early on Thursday, which had been captured by ISIL fighters when they overran Mosul in June 2014.

ISIL's strategy reportedly includes waiting for "darkness to fall" before hidden fighters launch a series of attacks on surrounding soldiers.

Iraqi forces aim to secure the airport and the camp's surrounding areas, in order to easily bring in reinforcements, Al Jazeera's Bin Javaid said, adding that "Iraqi forces realise that taking Mosul is weeks, if not months away".

A federal police officer and an official overseeing operations said on Friday that soldiers secured key infrastructures since the operation to force ISIL out of western Mosul was officially launched on Sunday.

The operation to retake Iraq's second-largest city was officially launched in October last year, and in January its eastern half was declared "fully liberated".

Mosul is ISIL's last major urban stronghold in Iraq, but the battle to retake its western half is expected to be the most challenging yet, since the streets are older, narrower and is densely populated with an estimated 750,000 civilians trapped in the area.

In a separate incident, two suicide car bombers struck army and paramilitary forces west of Mosul on Monday, killing and wounding a number of troops, two army officers said, with ISIL claiming responsibility for the attacks.